Nearsightedness is often first detected during childhood and is commonly diagnosed between the early school years through the teens. A child with nearsightedness may:

Persistently squint

Need to sit closer to the television, movie screen or the front of the classroom

Seem to be unaware of distant objects

Blink excessively

Rub his or her eyes frequently

When to see a doctor

If your difficulty clearly seeing things that are far away is pronounced enough that you can't perform a task as well as you wish, or if the quality of your vision detracts from your enjoyment of activities, see an eye doctor. He or she can determine the degree of your nearsightedness and advise you of your options to correct your vision.

Seek emergency medical care if you experience a sudden onset of flashes of floaters or a shadow covering part of your field of vision. These are warnings signs of retinal detachment, which is a rare complication of myopia. Retinal detachment is a medical emergency, and time is critical.

Regular eye exams

Since it may not always be readily apparent that you're having trouble with your vision, the American Academy of Ophthalmology recommends the following intervals for regular eye exams:

Adults

If you're at high risk of certain eye diseases, such as glaucoma, get an eye exam every two to four years up to age 40, then every one to three years between 40 and 54, and every one to two years beginning at age 55.

If you don't wear glasses or contacts, have no symptoms of eye trouble, and are at a low risk of developing eye diseases, such as glaucoma, get an eye exam at the following intervals.

An initial exam at 40

Every two to four years between ages 40 and 54

Every one to three years between ages 55 and 64

Every one to two years beginning at age 65

If you wear glasses or contacts, you'll likely need to have your eyes checked regularly. Ask your eye doctor how frequently you need to schedule your appointments. But, if you notice any problems with your vision, schedule an appointment with your eye doctor as soon as possible, even if you've recently had an eye exam. Blurred vision, for example, may suggest you need a prescription change, or it could be a sign of another problem.

Children and adolescents

Children need to be screened for eye disease and have their vision tested by a pediatrician, an ophthalmologist or another trained screener at the following ages and intervals.

During the newborn period

At well-child visits until school age

During school years, every one to two years at well-child visits, or through school or public screenings

Nearsightedness usually occurs when your eye is too long or has a cornea that's curved too steeply. This causes the light rays entering each eye to focus in front of the retina, instead of on the retina, leading to blurry images. The exact reason for some people developing longer eyes is unknown, but it may be related to genetics or environmental conditions.

Normal vision

To focus the images it sees, your eye relies on two critical parts:

The cornea, the clear front surface of your eye

The crystalline lens, a clear structure inside your eye that changes shape to help focus objects

In a normally shaped eye, each of these focusing elements has a perfectly smooth curvature like the surface of a smooth rubber ball. A cornea and lens with such curvature bend (refract) all incoming light in such a way as to make a sharply focused image on the retina, at the back of your eye.

A refractive error

However, if your cornea or lens isn't evenly and smoothly curved, light rays aren't refracted properly, and you have a refractive error. Nearsightedness is one type of refractive error. Instead of being focused precisely on your retina, light is focused in front of your retina, resulting in a blurry appearance of distant objects.

Other refractive errors

In addition to nearsightedness, other refractive errors include:

Farsightedness (hyperopia). This occurs when your cornea is curved too little or your eye is shorter from front to back than normal. The effect is the opposite of nearsightedness. In adults, both near and distant objects are blurred.

Astigmatism. This occurs when your cornea or lens is curved more steeply in one direction than in another. Uncorrected astigmatism blurs your vision.

Certain risk factors may increase the likelihood of developing nearsightedness, such as:

Family history. Nearsightedness tends to run in families. If one of your parents is nearsighted, your risk of developing the condition is increased. The risk is even higher if both parents are nearsighted.

Reading. People who do a lot of reading may be at increased risk of myopia.

Environmental conditions. Some studies support the idea that a lack of time spent outdoors may increase the chances of developing myopia.

Nearsightedness may be associated with several complications, such as:

Reduced quality of life. Uncorrected nearsightedness can affect your quality of life. You might not be able to perform a task as well as you wish. And your limited vision may detract from your enjoyment of day-to-day activities.

Eyestrain. Uncorrected nearsightedness may cause you to squint or strain your eyes to maintain focus. This can lead to eyestrain and headaches.

Impaired safety. Your own safety and that of others may be jeopardized if you have an uncorrected vision problem. This could be especially serious if you are driving a car or operating heavy equipment.

Other eye problems. Severe nearsightedness puts you at a slightly increased risk of retinal detachment, glaucoma and cataracts.

You may encounter three kinds of specialists as you seek help for various eye conditions:

Ophthalmologist. An ophthalmologist is an eye specialist with a doctor of medicine (M.D.) or a doctor of osteopathy (D.O.) degree who provides full eye care. This care includes performing complete eye evaluations, prescribing corrective lenses, diagnosing and treating common and complex eye disorders, and performing eye surgery when it's necessary.

Optometrist. An optometrist has a doctor of optometry (O.D.) degree. Optometrists are trained to evaluate vision, prescribe corrective lenses and diagnose common eye conditions.

Optician. An optician is a specialist who helps fit people for eyeglasses or contact lenses, following prescriptions from ophthalmologists and optometrists. Some states require opticians to be licensed. Opticians are not trained to diagnose or treat eye disease.

No matter which type of eye specialist you choose, here's some information to help you get ready for your appointment.

What you can do

If you already wear glasses, bring them with you to your appointment. Your doctor has a device that helps to determine what type of prescription you already have. If you wear contacts, bring to your appointment an empty contact lens box from each type of contact you use.

List any symptoms you're experiencing, such as trouble reading up close or difficulty with night driving.

Make a list of all medications, vitamins or supplements that you're taking.

List questions to ask your doctor.

Preparing a list of questions can help you make the most of your visit. For nearsightedness, some basic questions to ask include:

When do I need to use corrective lenses?

What are benefits and drawbacks to glasses?

What are benefits and drawbacks to contacts?

How often do you recommend that I have my eyes examined?

Are more permanent treatments, such as eye surgery, an option for me?

If so, which do you recommend?

What types of side effects are possible from these treatments?

Will my insurance company pay for surgical procedures or a contact lens fitting?

Do you have any brochures or other printed material that I can take home with me? What websites do you recommend?

What to expect from your doctor

Do others in your family use glasses or contacts? Do you know how old they were when they first began having trouble with their vision?

When did you first begin wearing glasses or contacts?

Do you have any medical problems, such as diabetes?

Have you started to take any new medications, supplements or herbal preparations?

Nearsightedness is diagnosed by an eye exam. A complete eye exam involves a series of tests. Your eye doctor may use various instruments, aim bright lights directly at your eyes and ask you to look through several lenses. Your doctor uses these tests to examine different aspects of your eyes and vision and to determine the prescription needed to provide clear vision with eyeglasses or contact lenses.

The goal of treating nearsightedness is to improve vision by helping focus light on your retina through the use of corrective lenses or refractive surgery.

Corrective lenses

Eyeglasses. This is a simple, safe way to correct vision problems caused by myopia. The variety of eyeglasses is wide and includes bifocals, trifocals and reading lenses.

Contact lenses. These lenses are worn right on your eyes. They are available in a variety of types and styles, including hard, soft, extended wear, disposable, rigid gas permeable and bifocal. Ask your eye doctor about the pros and cons of contact lenses and what might be best for you.

Refractive surgery

Refractive surgery improves vision and reduces the need for eyeglasses or contact lenses. Your eye surgeon uses a laser beam to reshape the cornea. This type of surgery has become routine, but it's usually not recommended until the eyes have fully developed, in the 20s.

Refractive surgical procedures for nearsightedness include:

Laser-assisted in-situ keratomileusis (LASIK). With this procedure, your eye surgeon makes a thin, hinged flap in your cornea. He or she then uses an excimer laser to remove layers from the center of your cornea to flatten its domed shape.

An excimer laser differs from other lasers in that it doesn't produce heat. After the excimer laser is used, the thin corneal flap is repositioned.

Laser-assisted subepithelial keratectomy (LASEK). Instead of creating a flap in the cornea, the surgeon creates a flap only in the cornea's thin protective cover (epithelium). He or she then uses an excimer laser to reshape the cornea's outer layers and flatten its curvature and then repositions the epithelial flap. You may need to wear a bandage contact lens for several days afterward to encourage healing.

Photorefractive keratectomy (PRK). This procedure is similar to LASEK, except the surgeon removes the epithelium. It will grow back naturally, conforming to your cornea's new shape. You may need to wear a bandage contact lens for a few days afterward.

Intraocular lens (IOL) implant. These lenses are surgically implanted into the eye, in front of the eye's natural lens. They may be an option for people with moderate to severe myopia. IOL implants are not currently considered a mainstream treatment option.

Some of the possible complications that can occur after refractive surgery include:

Undercorrection or overcorrection of your initial problem

Visual side effects, such as a halo or starburst appearing around lights

Dry eye

Infection

Corneal scarring

Rarely, vision loss

Discuss the potential risks and benefits of these procedures with your eye doctor.

You can't prevent nearsightedness. Some studies suggest you may be able to slow its progression. You can help protect your eyes and your vision by following these tips:

Have your eyes checked. Do this regularly even if you see well.

Control chronic health conditions. Certain conditions, such as diabetes and high blood pressure, can affect your vision if you don't receive proper treatment.

Prevent eye injuries. Wear protective eyewear when doing certain things, such as playing sports, mowing the lawn, painting or using other products with toxic fumes.

Eat healthy foods. Try to eat plenty of fruits, leafy greens and other vegetables. And studies show that your eyes benefit if you also include in your diet fish high in omega-3 fatty acids, such as tuna and salmon.

Don't smoke. Just as smoking isn't good for the rest of your body, smoking can adversely affect your eye health as well.

Use the right corrective lenses. The right lenses optimize your vision. Having regular exams will ensure that your prescription is correct.

Reduce eyestrain. Look away from your computer or near-task work, including reading, every few minutes.

Recognize symptoms. You may have a serious medical problem if you have a sudden loss of vision in one eye, experience sudden hazy or blurred vision, or see flashes of light, black spots, or halos around lights. These may indicate certain conditions, such as glaucoma, stroke, or a retinal tear or detachment. See your doctor immediately if you experience any of these symptoms.

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